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United States Patent |
5,599,110
|
MacKendrick
|
February 4, 1997
|
Bearing for a pressurized protective suit
Abstract
A pressure sealing bearing (13) for use in a protective environmental suit
(10) is provided. The bearing employs inner and outer races (44,54)
composed of a light weight, relatively weak material, such as a plastic or
aluminum alloy. To provide long wear and adequate strength, the bearing
includes contoured race wires (46,48,56,58) and an interlock mechanism
(72,74). The ends of inner race wire 48 are designed to butt against one
another to control the deformation due to compression of the inner race
(44) when pressure is applied to the bearing. The ends of outer race wire
56 include interlocking hooks (82,84) which control the deformation due to
tension of the outer race (54). In this way, the bearings achieve the
performance of all stainless steel bearings while providing weight
reductions of at least 60%.
Inventors:
|
MacKendrick; Robert R. (Milford, CT)
|
Assignee:
|
Airlock, Incorporated (Milford, CT)
|
Appl. No.:
|
483387 |
Filed:
|
June 7, 1995 |
Current U.S. Class: |
384/501; 2/2.12; 384/513 |
Intern'l Class: |
F16C 033/61; A62B 017/00 |
Field of Search: |
384/499,501,502,507,508,513-516,520-522
2/2.12
|
References Cited
U.S. Patent Documents
3466061 | Sep., 1969 | Fonda-Bonardi | 2/201.
|
3533497 | Oct., 1970 | Rojewski | 384/501.
|
3743368 | Jul., 1973 | Elkins et al. | 384/485.
|
4568205 | Feb., 1986 | Basener | 384/501.
|
4596054 | Jun., 1986 | MacKendrick et al.
| |
4598427 | Jul., 1986 | Vykukal | 2/2.
|
4797008 | Jan., 1989 | Helbig et al. | 384/501.
|
5068919 | Dec., 1991 | MacKendrick et al.
| |
5071264 | Dec., 1991 | Franke et al. | 384/501.
|
Other References
JC Engineering International Ltd.'s product brochure entitled "Ultra Slim
Bearings", 1984.
Rotek Incorporated's product brochure entitled "Large-Diameter Ball and
Roller Bearings" 1973, p. 7.
Wireglide Bearings, Inc.'s product brochure entitled "USB-Ultra Slim
Bearings, Wire Race Bearings, Wire Elements, Retrofit Services", 1985.
|
Primary Examiner: Hannon; Thomas R.
Attorney, Agent or Firm: Klee; Maurice M.
Claims
What is claimed is:
1. A pressure sealing bearing for maintaining a predetermined pressure
comprising:
(a) an inner race;
(b) at least one inner race wire carried by the inner race;
(c) an outer race;
(d) at least one outer race wire carried by the outer race, said inner and
outer race wires defining an annular cavity in the assembled bearing;
(e) a plurality of ball bearings in the annular cavity;
(f) a plurality of spacers between the ball bearings;
(g) at least one pressure seal between the inner race and the outer race;
and
(h) interlock means between the inner race and the outer race for
restraining deformation of those races relative to one another at
pressures above the predetermined pressure.
2. A pressure sealing bearing for maintaining a predetermined pressure
comprising:
(a) an inner race;
(b) at least one inner race wire carried by the inner race, the ends of the
wire butting against each other at least when the pressure applied to the
bearing is above the predetermined pressure;
(c) an outer race;
(d) at least one outer race wire carried by the outer race, said inner and
outer race wires defining an annular cavity in the assembled bearing;
(e) a plurality of ball bearings in the annular cavity;
(f) a plurality of spacers between the ball bearings; and
(g) at least one pressure seal between the inner race and the outer race.
3. A pressure sealing bearing for maintaining a predetermined pressure
comprising:
(a) an inner race;
(b) at least one inner race wire carried by the inner race;
(c) an outer race;
(d) at least one outer race wire carried by the outer race, said inner and
outer race wires defining an annular cavity in the assembled bearing, the
ends of the outer race wire being locked together;
(e) a plurality of ball bearings in the annular cavity;
(f) a plurality of spacers between the ball bearings; and
(g) at least one pressure seal between the inner race and the outer race.
4. A pressure sealing bearing for maintaining a predetermined pressure
comprising:
(a) an inner race;
(b) at least one inner race wire carried by the inner race, the ends of the
wire butting against each other at least when the pressure applied to the
bearing is above the predetermined pressure;
(c) an outer race;
(d) at least one outer race wire carried by the outer race, said inner and
outer race wires defining an annular cavity in the assembled bearing, the
ends of the outer race wire being locked together;
(e) a plurality of ball bearings in the annular cavity;
(f) a plurality of spacers between the ball bearings;
(g) at least one pressure seal between the inner race and the outer race;
and
(h) interlock means between the inner race and the outer race for
restraining deformation of those races relative to one another at
pressures above the predetermined pressure.
5. The pressure sealing bearing of claim 3 or 4 wherein the ends of the
outer race wire are locked together by interlocking hooks formed at the
ends.
6. The pressure sealing bearing of claim 5 wherein each of the interlocking
hooks comprises an undercut mating surface.
7. The pressure sealing bearing of claim 3 or 4 wherein the ends of the
outer race wire are locked together by means of a link.
8. The pressure sealing bearing of claim 1, 2, 3, or 4 wherein the inner
and outer races are each composed of a non-metallic material.
9. The pressure sealing bearing of claim 1, 2, 3, or 4 wherein the inner
and outer races are each composed of a metallic material having a density
of less than about three grams per cubic centimeter.
10. The pressure sealing bearing of claim 9 wherein the material is an
aluminum alloy.
11. The pressure sealing bearing of claim 1, 2, 3, or 4 wherein a pressure
seal is located on each side of the annular cavity.
12. A suit having an internal volume which can be pressurized to a
predetermined pressure, said suit comprising:
a first suit section;
a second suit section; and
a rotatable joint between the first suit section and the second suit
section, said rotatable joint comprising at least one pressure sealing
bearing which comprises:
(a) an inner race;
(b) at least one inner race wire carried by the inner race;
(c) an outer race;
(d) at least one outer race wire carried by the outer race, said inner and
outer race wires defining an annular cavity in the assembled bearing;
(e) a plurality of ball bearings in the annular cavity;
(f) a plurality of spacers between the ball bearings; and
(g) at least one pressure seal between the inner race and the outer race
for maintaining the suit's internal pressure upon pressurization.
13. The suit of claim 12 further comprising interlock means between the
inner race and the outer race for restraining deformation of those races
relative to one another at internal pressures above the predetermined
pressure.
14. The suit of claim 12 wherein the ends of the inner race wire butt
against each other at least when the suit is pressurized to a pressure
above the predetermined pressure.
15. The suit of claim 12 wherein the ends of the outer race wire are locked
together.
16. The suit of claim 12 wherein:
the ends of the inner race wire butt against each other at least when the
suit is pressurized to a pressure above the predetermined pressure;
the ends of the outer race wire are locked together; and
the pressure sealing bearing comprises interlock means between the inner
race and the outer race for restraining deformation of those races
relative to one another at internal pressures above the predetermined
pressure.
17. The suit of claim 15 or 16 wherein the ends are locked together by
interlocking hooks formed at the ends.
18. The suit of claim 17 wherein each of the interlocking hooks comprises
an undercut mating surface.
19. The pressure sealing bearing of claim 15 or 16 wherein the ends are
locked together by means of a link.
20. The suit of claim 12 wherein the inner and outer races are each
composed of a non-metallic material.
21. The suit of claim 12 wherein the inner and outer races are each
composed of a metallic material having a density of less than about three
grams per cubic centimeter.
22. The suit of claim 21 wherein the metallic material is an aluminum
alloy.
23. The suit of claim 12 wherein a pressure seal is located on each side of
the annular cavity.
Description
FIELD OF THE INVENTION
This invention relates to pressurized protective suits and, in particular,
to an improved bearing for use in forming the joints of such a suit.
BACKGROUND OF THE INVENTION
Pressurized protective suits are used in hostile environments, such as,
environments containing hazardous materials and in high altitude
environments, including outer space. Pressurization of such suits causes
them to become rigid so that the user's movements when wearing the suit
can be severely restricted. Accordingly, such suits include a variety of
joints so that the user can perform tasks while wearing the suit. These
joints have included neck joints, shoulder joints, elbow joints, wrist
joints, waist joints, hip and thigh joints, knee joints, and ankle joints.
To provide ease of movement, prior joints have included low friction
bearings. In addition to low friction, these bearings have also had low
leakage so as to maintain a separation between the internal environment of
the suit and the external environment. MacKendrick et. al., U.S. Pat. No.
4,596,054, shows a construction of a prior art low friction, low leakage
bearing which employs ball bearings held in integral metal races with the
dynamic interface between the races being sealed by an elastomeric lip
seal.
One of the critical criteria for a pressurized protective suit which is to
be used in a "one g" environment is the overall weight of the suit.
Overall weight is also important for suits which are to be used in outer
space since the training of astronauts in such suits often takes place on
earth. To date, weight minimization has involved the use of relatively
light weight materials, such as, plastics, polymer reinforced fabrics, and
the like, to form the body of the suit.
Because of their criticality, the bearings used in the joints of
pressurized protective suits have continued to be made of relatively heavy
metals. Prior to the present invention, light weight bearings composed
substantially of non-metallic materials have not been available to the
art. In the early days of the space program, bearings made of aluminum
were used, however, those bearing were found to wear rapidly and, as a
result, are no longer used. Instead, stainless steel bearings are used
which are both heavier and more expensive than bearings made of aluminum.
The challenge to the art has been to produce bearings which have low
torque, high reliability, and long life cycle properties which are
comparable to bearings made from high density metals and which, at the
same time, have a significantly reduced weight in comparison to such heavy
bearings.
In addition to the foregoing properties, the desired light weight bearings
need to have pressure retaining characteristics sufficient to withstand
the internal pressures used in pressurized protective suits, i.e., the
bearings must exhibit very low leak at the operating pressure of the suit.
In general terms, the higher the pressure the bearing can withstand
without developing significant (higher) torque, the better.
Bearings employing race wires have been commercially produced. See, for
example, Wireglide Bearings, Inc.'s product brochure entitled "USB-Ultra
Slim Bearings, Wire Race Bearings, Wire Elements, Retrofit Services",
1985; JC Engineering International Ltd.'s product brochure entitled "Ultra
Slim Bearings", 1984; and Rotek Incorporated's product brochure entitled
"Large-Diameter Ball and Roller Bearings" 1973, page 7. These bearings,
however, have not had low leak characteristics and have not been used in
constructing the joints of pressurized protective suits.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of this invention to provide
improved bearings for use in constructing pressurized protective suits. In
particular, it is an object of the invention to provide bearings which are
substantially lighter than the bearings currently used for such purposes
but still have operational characteristics which provide a joint suitable
for use in a protective suit.
To achieve these and other objects, the invention in accordance with
certain of its aspects provides a protective suit which has an internal
volume which can be pressurized to a predetermined pressure and which
comprises at least one bearing which provides a pressure seal, i.e., a
pressure sealing bearing, which comprises:
(a) an inner race, which is preferably composed of a non-metallic material;
(b) at least one inner race wire carried by the inner race;
(c) an outer race, which is preferably composed of a non-metallic material;
(d) at least one outer race wire carried by the outer race, said inner and
outer race wires defining an annular cavity in the assembled bearing;
(e) a plurality of ball bearings in the annular cavity, which may be made
of a non-metallic material;
(f) a plurality of spacers between the ball bearings, which may be made of
a non-metallic material; and
(g) at least one pressure seal between the inner race and the outer race
for maintaining the suit's internal pressure (e.g., two pressure seals,
one on each side of the annular cavity).
In certain preferred embodiments, the bearing further comprises interlock
means between the inner race and the outer race for restraining
deformation of those races relative to one another at suit pressures above
the predetermined pressure.
In other preferred embodiments, the ends of the inner race wire butt
against each other at least when the suit is pressurized to a pressure
above the predetermined pressure (i.e., the ends can begin butting
together at pressures below the predetermined pressure), so that the
diameter of the wire cannot be reduced below a predetermined value as a
result of compressive forces generated in the wire by the internal
pressure within the suit.
In further preferred embodiments, the ends of the outer race wire are
locked together, e.g., by interlocking hooks formed at the ends, so that
the diameter of the wire remains constant under tension forces generated
in the wire by the internal pressure within the suit.
These preferred embodiments of the pressure sealing bearings can be used in
applications other than pressurized protective suits if desired.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a protective suit in which the bearings of the
present invention can be used.
FIG. 2 is a cross-sectional view of a shoulder joint employing four
bearings constructed in accordance with the present invention.
FIG. 3 is an expanded, cross-sectional view of the bearing labelled 130 in
FIG. 2.
FIG. 4 is a cross-sectional view of a race wire for use in the bearing of
the present invention.
FIG. 5 is a side view of a preferred mechanism for locking together the
ends of the outer race wire of the bearing of the invention.
The foregoing drawings, which are incorporated in and constitute part of
the specification, illustrate the preferred embodiments of the invention,
and together with the description, serve to explain the principles of the
invention. It is to be understood, of course, that both the drawings and
the description are explanatory only and are not restrictive of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As discussed above, the present invention relates to pressure sealing
bearings for use in pressurized protective suits.
FIG. 1 shows such a pressurized protective suit 10 having ankle joints 12,
knee joints 14,16,18, thigh and hip joints 20,21, waist joint 22, shoulder
joint 24, elbow joints 26,28, and wrist joint 30. The bearings of the
present invention can be used in the construction of these or other joints
in a pressurized protective suit.
FIG. 2 shows a shoulder joint employing four pressure sealing bearings 13
constructed in accordance with the invention. The upper end of the
shoulder joint is shown at 32 in FIG. 2 and the lower end at 34. Threads
36 at the lower end are used to attach the joint to an upper arm section
of the suit. Other means of attachment known in the art can be used if
desired. Similarly, an attachment means (not shown) is used at upper end
32 to attach the shoulder joint to a torso section of the suit.
Shoulder joint 24 is composed of three wedge-shaped sections 38,40,42. Each
end of each wedge-shaped section carries a bearing 13 constructed in
accordance with the invention. As shown in FIG. 2, wedge-shaped sections
38,40,42 are formed integrally with bearings 13 and are thus composed of
the same material as the bearing races. It is to be understood that other
configurations can be used if desired, including, for example, the
attachment of fabric sections to the end surfaces of the bearings.
FIG. 3 is an enlarged view of the bearing labelled 130 in FIG. 2. The
remaining bearings of FIG. 2 have the same construction. The high pressure
side of the bearing is on the left in FIG. 2, and the low pressure side,
e.g., the hostile environment side, is on the right.
Bearing 13 includes the following components:
(a) inner race 44;
(b) inner race wires 46,48 which are mounted in (carried by) grooves 50,52
in inner race 44;
(c) outer race 54;
(d) outer race wires 56,58 which are mounted in (carried by) grooves 60,62
in outer race 54;
(e) annular cavity 64 (see FIG. 2) defined by inner and outer race wires
46,48,56,58;
(f) a plurality of ball bearings 66 in the annular cavity, one of which is
shown in FIG. 3;
(g) a plurality of spacers (not shown) between the ball bearings to prevent
binding of the ball bearings during rotation of the joint (note that the
spacers can comprise smaller ball bearings, small pellets, or a cage for
the ball bearings);
(h) pressure seals 68,70 between inner race 44 and outer race 54 for
maintaining the internal pressure of the suit when pressurized;
(i) interlock means 72,74 between inner race 44 and outer race 54 for
restraining deformation of the inner and outer races relative to one
another at internal pressures above the suit's normal operating pressure
(predetermined pressure) and during unusual loading of the bearing by the
user; and
(j) ball feed port 76 (see FIG. 2) for introducing the ball bearings and
the spacers into annular cavity 64 (note that after the balls and spacers
are introduced, feed port 76 can be sealed using a plug (not shown)
retained by, for example, screws).
Inner race 44 and outer race 54 can be made of a variety of materials.
Preferred materials are those having a low density, e.g., a density less
than about 3 grams/cubic centimeter. The material can be a light metal,
such as an aluminum alloy, e.g., A 356 aluminum, or a plastic material,
such as, an ultrahigh molecular weight polyethylene, a carbon composite, a
PEEK polymer, or the like. When a plastic material is used, it can include
various fillers and other ingredients known in the polymer art.
In many cases, the race material will have a low yield, e.g., a yield of
about 30,000 pounds per square inch in the case of aluminum and about
15,000 pounds per square inch (psi) and below in the case of plastics.
Nevertheless, as illustrated in the examples, the bearings of the
invention can withstand substantial internal pressures.
The races are generally formed by machining, but also can be cast,
injection molded, laid up in the case of composites, or formed by other
conventional techniques.
The weight reductions achieved by using lighter materials for the races are
significant. For example, protective suits currently used in the U.S.
space program typically weigh about 150 pounds (without backpack) and can
include at least 20 stainless steel bearings having a combined weight of
at least 35 pounds. By means of the invention, at least a 60% reduction in
this weight can be achieved by substituting an aluminum alloy for the
stainless steel. When made out of such an alloy, the bearings will weigh
less than 20 pounds, thus reducing the overall weight of the suit by more
than 10%. Even greater reductions will result from the use of low weight
plastic materials to construct the bearing races.
Race wires 46,48,56,58 are generally composed of a metallic material, such
as stainless steel, but can be composed of other types of materials
provided the material has sufficient hardness and strength to maintain the
integrity of the bearing during loading under the expected range of
pressures.
FIG. 4 shows a cross-section through race wire 48. As shown therein, the
race wire comprises a body 78 having a cut-out portion 80 designed to mate
with ball bearings 66. Cut-out portion 80 can, for example, have the
configuration of a conventional ball bearing race. Cut-out 80 can be
formed in the race wire by machining, grinding, or the like.
FIGS. 2 and 3 show the use of four race wires for each bearing 13. If
desired, a single race wire can be used with either the inner or outer
race or with both the inner and outer races. The single wire, when used,
is located where the internal pressure applies force to the bearing's
races, i.e., in FIG. 3, race wires 48 and 56 must be retained. In general,
it is preferred to use four race wires.
It should be noted that wire 48 is in compression and wire 56 is in tension
for pressure on the left hand side of FIG. 3. To avoid excessive changes
in the length of wire 48 in response to such compressive force, the wire
is preferably sized to have a length such that the ends of the wire butt
against each other when the suit is pressurized so that the diameter
(circumference) of the wire cannot be reduced below a predetermined value.
The predetermined value is selected so as to limit the change in size of
the inner race as a result of compression to a value low enough so that
the seal provided by the bearing is not compromised. Preferably, wire 48
has a length which is just slightly less than the length of groove 52 so
that the wire can be conveniently inserted in the groove.
To avoid changes in the length of wire 56 in response to tension forces
generated in the wire by the internal pressure within the suit, the wire
preferably includes means for locking its ends together. FIG. 5 shows a
preferred form of such a locking mechanism. As shown therein, interlocking
hooks 82,84 are formed at the ends of the wire race. Hook 82 is composed
of surfaces 86 through 94 which mate with surfaces 106 through 114 of hook
84 as shown in FIG. 5, i.e., surface 86 mates with surface 114, etc.
Surfaces 90 and 110 are undercut so as to resist separation when tension
is applied to the race wire. In particular, as shown in FIG. 5, edge 98 of
surface 90 lies to the left of edge 96 and similarly edge 118 of surface
110 lies to the left of edge 116. In this way, the desired undercut
relationship between surfaces 90 and 110 is achieved. The hook mechanism
of FIG. 5 can be formed in the race wire by various techniques including
wire EDM techniques, laser cutting techniques, and the like.
Other mechanisms for locking together the ends of the outer race wire can
be used if desired. For example, a separate link having a hook mechanism
at each end, e.g., a hook mechanism of the type shown in FIG. 5, can be
used to lock the outer race wire into a constant diameter (circumference)
circle. Such a link, if provided in different lengths, can be used to
adjust the cross-section of annular cavity 64 so as to achieve a preload
of ball bearings 66. Such a preload can, in some circumstances, minimize
the effect of ball blocking. Other mechanisms for locking the ends of the
wire race together include the use of laser or TIG welding.
It should be noted that the butting together and locking mechanisms for the
race wires can be omitted, if desired, when materials having a relatively
high yield strength, e.g., aluminum alloys, are used in the practice of
the invention.
Ball bearings 66 are typically made of stainless steel and the spacers
between the balls are typically made of plastic. If desired, the ball
bearings can be made of a non-metallic material, such as a ceramic.
Pressure seals 68,70 are preferably constructed in accordance with
MacKendrick et al., U.S. Pat. No. 4,596,054, the relevant portions of
which are incorporated herein by reference. A suitable material for the
seal is a flexible polyurethane. Other seal designs and materials can be
used if desired. As shown in the figures, bearing 13 includes two seals,
one on each side of annular cavity 64. Such a configuration is preferred
for spacesuit applications where redundancy is desirable. In other
applications, a single seal can be used. Such a single seal will typically
be on the pressurized side of the bearing, i.e., seal 68 in FIG. 3, so
that ball feed port 76 (FIG. 2) does not have to be sealed.
Interlock means 72,74 serves the important function of restraining
deformation of the inner and outer races relative to one another at
pressures above the bearing's normal operating pressure. The interlock
means also protects the bearing from unusual loads which may occur during
use, e.g., during the handling of massive objects. Such restraining helps
prevent failure of the bearing's seal. In more extreme cases, the
restraining helps prevent complete failure of the bearing through
dislocation of the race wires and release of the ball bearings. The
restraining is especially important when materials having a low yield
strength, such as plastics, are used to construct the races. With stronger
materials such as aluminum alloys, the interlock can be omitted if
desired.
As shown in FIG. 3, the interlock has a tongue and groove configuration
which can be readily formed in races 44,54. The dimensions and tolerances
of the interlock components are selected to 1) provide engagement between
the tongue and the groove at a level of distortion of the races less than
that which would cause pressure seals 68,70 to open, 2) provide sufficient
strength to the tongue to withstand the expected distorting forces, e.g.,
the tongue is made relatively short so that large moments are not
generated, and 3) provide adequate clearance between the tongue and groove
so that these components remain out of contact during normal operation.
The clearance levels can be made relatively small for plastic races since
the coefficient of friction for most plastics is low.
Configurations other than those shown can, of course, be used for the
interlock mechanism if desired. For example, the interlock need not be
located at the interface between the inner and outer races but can be
located away from that interface. Also, the interlock need not be
symmetric for the low pressure and high pressure sides of the bearing,
e.g., the interlock on the high pressure side can be located at the
interface between the inner and outer races and that on the low pressure
side can be located outward from the circumferential centerline of the
bearing. It should be noted that in addition to restraining deformations
of the races, the interlock serves to protect the bearing from
contamination by materials released within the suit, as well as those in
the outside environment.
Without intending to limit it in any manner, the present invention will be
more fully described by the following examples.
EXAMPLE 1
Life Cycle Testing
A pressure sealing bearing was constructed in accordance with the
configuration of FIG. 3, except that only a single pressure seal was used
and the race wires did not include a locking mechanism and did not butt
together. The pressure seal was located on the high pressure side of the
bearing, i.e., it was seal 68 in FIG. 3.
Races 44,54 were made of ultra high molecular weight polyethylene having a
density of about 0.9 grams/cc and a yield strength of about 3,400 psi.
Race wires 46,48,56,58 were constructed of stainless steel and had the
configuration of FIG. 4. Stainless steel ball bearings having a nominal
diameter of 3/16 inches were used along with DELRIN spacer balls whose
diameters were 4-5 thousandths smaller. Seal 68 was made of a flexible
polyether polyurethane having a durometer value of about 70.
The bearing was subjected to life testing by being rotated back and forth
by 180.degree. for over 13,000 cycles at a rotation rate of
90.degree./second. The pressure applied to the bearing during these tests
was 4.3 psi, the standard operating pressure for a space suit.
Leakage was monitored continuously during the testing and was found to be
essentially zero at all times and thus equivalent to the current state of
the art bearings.
Torque was also measured throughout the testing and was found to be
essentially constant at about 2 inch-pounds at all times. This torque
value is comparable to that achieved with bearings constructed entirely of
stainless steel, i.e., bearings employing stainless steel races and no
race wires.
As discussed above, the bearing used in this test is significantly lighter
than the all stainless steel bearings currently in use in the art. Yet, as
this data show, the bearing was able to achieve performance levels
suitable for use in space suit applications.
EXAMPLE 2
Pressure Testing
The bearing of Example 1 was subjected to an overpressure test in which
increasing pressure was applied to the bearing until a substantial
overpressure condition was reached, namely, a pressure of 35 psi. The
bearing was found to easily withstand this level of pressure.
To demonstrate the importance of the interlock mechanism, that mechanism
was removed from the bearing and the test was repeated. In this case,
failure of the bearing occurred at a pressure of 28 psi. The failure mode
exhibited was a separation of the races with release of the ball bearings.
Based on this data, the interlock provided at least a 25% increase in the
amount of pressure which the bearing could withstand.
Further pressure testing was performed with the bearing of Example 1 but
with the race wire locking mechanism of FIG. 5 and without the interlock
mechanism of FIG. 3. For this configuration, the bearing withstood a
pressure of approximately 50 psi without separation of the races, at which
point the experiment was stopped. A further test was performed with the
pressure seal located on the low pressure side of the bearing and with the
interlock removed. For this configuration, it was found that the bearing
withstood a pressure of approximately 25 psi without separation of the
races, at which point the experiment was stopped. In both of the foregoing
experiments in which the interlock mechanism was removed, leakage of the
seal was observed beginning at pressures in the 10-15 psi range.
The foregoing data show that the interlock and wire lock mechanisms of the
invention provide substantial increases in the amount of pressure which
the bearing can withstand. They thus allow the bearing to be composed of
weak materials and still provide significant pressure resisting
properties.
Although preferred and other embodiments of the invention have been
described herein, other embodiments may be perceived by those skilled in
the art without departing from the scope of the invention as defined by
the following claims.
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